The scientific library “Elena and Ivan Duichevi” contains about 60,000 library items and is one of the richest documentary bases for the study of Bulgarian , Byzantine and Western Medieval history , art, literature and paleography .

It includes Greek manuscripts in Bulgaria (app. 500 codes) , more than 70 Slavic and 200 Oriental, bilingual and trilingual manuscripts from IX to XIX century. Therefore, the manuscript collection is highly representative of the various linguistic traditions on the Balkans: Greek, Slavic and Oriental. The acquisitions are made through purchases with financial support raised by target donations. Scientific treatment , restoration and conservation of the manuscript and archival collections is performed under several international projects with colleagues from various institutes at home and abroad (Japan Foundation, Sumitomo Foundation, Vaseda University - Tokyo, the restoration laboratory of Graz - Austria , Prof . Agamemnon Tselikas - Director of the Institute of History and Paleography at the Cultural Foundation of the National Bank of Greece, Athens, etc.). The archival wealth of the Centre for Slavo-Byzantine Studies “Prof. Ivan Dujčev” includes scientific archives and heritage epistle of prominent university professors - Ivan Duichev , Nikola Mihov , Todor Borov , Asen Vasiliev and Velizar Velkov . Epistle corpus includes 20,000 letters of these scholars, as well as records of expeditions to Mount Athos and the Balkans, meetings of the Faculty of History - documents related to the history of Sofia University.